SKF Sensor-Bearing Units – concentrate intelligence in your motion control

Contents

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1 Product information.................................................. 3Ball bearing + Sensor = Sensor-Bearing Unit ........... 3What is an SKF Sensor-Bearing Unitand how does it work?.................................................. 4Why SKF Sensor-Bearing Unit? ................................... 4This is the answer......................................................... 6Small, yet great............................................................. 6Electro-magnetic compatibility ...................................... 7When quality and reliability count ................................. 8

2 Recommendations ................................................... 12Application of units ...................................................... 12Selection of bearing size .............................................. 12Unit arrangement .......................................................... 12Electrical interface data ................................................ 14Mounting ....................................................................... 14Lubrication and maintenance ....................................... 15

3 Product data.............................................................. 16General unit data .......................................................... 16Product table................................................................. 18

Other SKF bearing units .............................................. 20

The SKF Group – a worldwide organisation .............. 22

Made by SKF® stands for excellence. It symbolises our consistent endeavour to achieve total quality ineverything we do. For those who use our products.“Made by SKF” implies three main benefits.

Reliability – thanks to modern, efficient products, based on our worldwide application know-how, optim-ised materials, forward-looking designs and the most advanced production techniques.

Cost effectiveness – resulting from the favourable ratio between our product quality plus service facilities,and the purchase price of the product.

Market lead – which you can achieve by takingadvantage of our products and services. Increasedoperating time and reduced down-time, as well asimproved output and product quality are the key to a successful partnership.

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1 Product information 2 Recommendations 3 Product dataDesign features Page …………12 Page ............16

1+ =

Compared with the initial concept ofseparate components, the integrationof sensor, impulse ring and bearing,which was mainly driven by SKFefforts, was an important step towardshigher quality in signal generation andtransmission, more compact construc-tion and simpler design.

Bearings with integral sensors are no longer used only in vehicles, buthave spread to many other fields ofapplication. These are in the first placeSKF Sensor-Bearing Units used forrecording

� the number of revolutions� the speed� the direction of rotation� the relative position/counting� acceleration or deceleration

Clear information on the status of trav-elling machine parts is decisive inmany fields of engineering so as toenable reliable open-loop and closed-loop control of movements. Such infor-mation becomes all the more import-ant with the increasing necessity ofcreating more light-weight and simplerconstructions.

Basically, everything started with the implementation of anti-lock brakingsystems (ABS) in vehicles. “Intelligentbearings” were required to record thevariations of the circumferential speedof the wheel. From the very beginningSKF was involved in the developmentand subsequent improvement of thesebearings. Millions of these intelligentbearings have been supplied by SKFand operate reliably worldwide.

m/s

786

0

m/s2

Number of revolutions

Speed

Direction of rotation

Relative positioncounting

Acceleration ordeceleration

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1 Product information 2 Recommendations 3 Product dataDesign features Page …………12 Page ............16

What is an SKF Sensor-Bearing Unit ...SKF Sensor-Bearing Units are mecha-tronic machine components coveringthe fields of both sensor and bearingengineering. They are virtually an idealcombination of versatile deep grooveball bearings with sensor units shield-ed from external influences. Sensorbody, impulse ring and bearing aremechanically attached to each other,forming an integral ready-to-mountunit.

... and how does itwork?A magnetic impulse ring divided into a sequence of north and south poles is attached to the inner ring of the SKFSensor-Bearing Unit. The outer ringcarries a sensor body with embeddedHall cells.

When the inner ring rotates, theimpulse ring moves past the stationarysensor ring, generating a magneticfield of changing polarity. The sensoroutputs a pulse the frequency of whichdepends on the number of polaritychanges per second. Via the sensorbearing connection cable, the sensoroutput signal is transmitted to an elec-tronic unit normally developed by theuser. This unit evaluates the signal and provides application-specific infor-mation.

The sensor body contains two cells,the two output signals offset in phaseallowing determination of the directionof rotation (➔ fig ).1

Why SKF Sensor-Bearing Unit?Since the beginning of the 1980s SKFhas been intensively involved in sen-sorised bearings and has had a decis-ive influence on their development.Today SKF Sensor-Bearing Units aretechnically advanced products whichhave proved their superiority overother solutions time and time again.Our Sensor-Bearing Units are basedon this wealth of application-specificknowledge gathered over the pasttwenty years – yet another example of our expertise to your benefit. In factSKF Sensor-Bearing Units offer signifi-cant total cost reduction on both

� existing solutions, due to less needfor adaptation

� new projects, due to simpler and more compact design.

A BB

A

A

N

SN NS

S

B

clockwise B,Aanticlockwise A,B

inner ring rotation

sensor sensor

The output from the sensor is twosquare pulse signals with a 90° phasedifference which allow determination of the direction of rotation

1Fig

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1 Product information 2 Recommendations 3 Product dataDesign features Page …………12 Page ............16

1The SKF designed and patented

Sensor-Bearing Unit is a simple, robustand compact mechatronic machineelement – a combination of proven,high quality mechanics and advancedsensor technology. It consists of

� an SKF deep groove ball bearingwith one seal and

� an SKF active sensor, consisting of impulse ring and sensor body as well as a connecting cable capableof measuring even zero movement.

The SKF deep groove ball bearingThe single row SKF deep groove ballbearings are suitable for high speeds,robust in operation and do not requireany maintenance. They can accommo-date not only rather high radial loads,but also axial loads and serve aslocating bearings guiding the shaft axially in both directions. Furthermorethey are noted for their high manufac-turing accuracy, their low noise andfriction levels, the efficient sealing andthe grease filling ensuring mainten-ance-free operation for life.

The SKF active sensor unitThe SKF Sensor-Bearing Unit incorpo-rates an active sensor designed to becompact and robust, very close to anincremental encoder function. It pro-vides accurate measuring down to zerospeed. Its main components are theimpulse ring, the sensor body with thesensors and the connecting cable.

The composite magnetised impulsering is attached to the bearing innerring. Depending on the bearing size, it is divided into a certain number ofnorth and south poles. The number ofpulses per revolution normally rangesbetween 32 and 80.

The sensor body is attached to thebearing outer ring by an SKF patentedsolution. The sensor body has twocells, enabling the direction of rotationto be determined. The two sensors areoffset to each other in the sensorbody. In a small integrated circuit theycontain not only the Hall generator asan active element but also the elec-tronics for signal amplification andconversion. The analogue sinusoidalsignal generated by the Hall generatoris amplified and converted into a square-wave signal by a Schmitt trigger.

The sensors require an external voltage supply.

SKF guarantees the signals, 100 %checked at the manufacturing processlevel.

Their output signals are in phasequadrature, the leading signal depend-ing on the direction of rotation. Further-more two sensors enable double thenumber of pulses. Instead of 64 pulsesper revolution in a standard bearingthere are now 128 pulses per revolu-tion. When counting the rising and falling edges of the pulses a maximumaccuracy of 256 pulses per revolutioncan be attained, which corresponds toa resolution of 1,4 angular degrees.

The signal output is fed via an opencollector circuit. Speeds down to zerocan be recorded.

The SKF Sensor-Bearing Unit is suitable for operating temperatures ofup to +120 °C.

Proven qualitySKF Sensor-Bearing Unit – a construction ofproven, high qualitymechanics andadvanced sensortechnology

Axial locationThe bearing pro-vides radial loadsand locates theshaft axially in bothdirections

Well protectedThe bearing has a sheet steel re-inforced seal madeof wear-resistantnitrile rubber

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1 Product information 2 Recommendations 3 Product dataProven quality Page …………12 Page ............16

This is the answerSKF Sensor-Bearing Units are com-pact, robust, easy-to-mount and cost-saving machine elements for a widescope of applications in open-loop andclosed-loop control engineering. Theypresent a number of significant advan-tages to the user, as SKF Sensor-Bearing Units

� take up hardly more space than thebearing as such,

� help save weight and total costs,� require only standard bearing toler-

ances and normal machining of theadjacent parts,

� simplify considerably the installationsince they are ready-to-mount units,

� are lubricated for life and mainten-ance-free,

� are insensitive to environmentalinfluences and less prone to cor-rosion,

� do not require time-consumingadjustment or subsequent setting,

� do not require subsequent signalchecks,

� provide optimised signal generationand transmission,

� are robust and give output signals of uniform reliability,

� do not suffer from external electro-magnetic fields,

� are an attractive alternative com-pared to an incremental encoder.

Small, yet greatThe standard range of SKF Sensor-Bearing Units covers the usual sizesfor such applications from 15 to 45mm bore diameter.

The sensor unit is matched with therotational speed permissible for thesealed deep groove ball bearing, oneof its application scopes being thenormal encoder field.

SKF will always strive to give toppriority to customer requirements andto develop application-specific andcost-effective solutions in close co-operation with the customer.

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1 Product information 2 Recommendations 3 Product dataProven quality Page …………12 Page ............16

1Electro-magnetic compatibilityOne decisive factor of satisfactoryoperation of electronic systems is theirability to operate in difficult industrialenvironments without interfering witheach other.

Thanks to the specific SKF sensorintegration, the SKF Sensor-BearingUnits can be used in systems function-ing under most arduous electro-magnet-ic environment such as described inthe European Standard EN 50082-2 orsimilar.

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1 Product information 2 Recommendations 3 Product dataApplication examples Page …………12 Page ............16

When quality and reliability countHigh reliability, good signal quality,minimal liability to interference, com-pact design, simple mounting, longservice life, economical operation andlow total costs are requirements thatmust be met in many operations.

There is a large number of widely dif-fering applications for the SKF Sensor-Bearing Unit, e.g.

� for control of electric motors,� for control of linear actuators,� for control of steering systems� for speed synchronism,� for detection of speed and direction

of rotation, e.g. in electric vehicles,packaging machines, papermakingmachines, textile machines, sortingmachines, etc.

Further applications are conceivable.The application schemes described inthe following show how close co-oper-ation between SKF and the customercan solve special problems in practiceusing SKF Sensor-Bearing Units.

The requirements

� High reliability� Uniform and high signal quality� Minimal liability to interference� Insensitivity to vibration� Insensitivity to high temperatures� Compact design� Simple installation� Total cost savings

The applications

� Vehicles� Electric motors� Gear units� Conveying and handling systems� Linear actuators� Control units� Escalator synchronism� Elevator management� Roll, unroll, length measurement� Mechanical engineering

The SKF solution

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1 Product information 2 Recommendations 3 Product dataApplication examples Page …………12 Page ............16

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1 Product information 2 Recommendations 3 Product dataApplication examples Page …………12 Page ............16

Steer-by-wire in fork-lift trucksAn important prerequisite to improvedperformance of industrial trucks is theergonomic design of the driver’s seatand cabin preventing excessive driverfatigue.

The concept initially developed for a fork-lift truck, namely a steer-by-wiresystem equipped with two SKF Sensor-Bearing Units, avoids the inconven-ience of a steering column. The Sensor-Bearing Units record the steeringmovement of the steering wheel, transmit a steering angle set value signal to the electronic control unitwhich then calculates the required regulating distance for the wheel to besteered and triggers a steering motor.

Limited space was available for thebearing arrangement of the steeringwheel shaft and the sensor units. Thedesign had to be sufficiently robust toaccommodate all forces occurring inoperation and the sensor system hadto correspond to the legal security stipulations. SKF Sensor-Bearing Unitsadapted to this special application fulfilled these demands.

The unique SKF design of Sensor-Bearing Units is also successfullyused in various other steer-by-wire orposition control systems, such asmarine and military applications, off-road and agricultural vehicles, as wellas industrial handling systems.

SKF steer-by-wire module for industrial vehicles

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1 Product information 2 Recommendations 3 Product dataApplication examples Page …………12 Page ............16

1Motor control in three-phasedrivesThe conversion from direct current drives to more versatile, robust andvirtually maintenance-free three-phasedrives made an electronic circuit withsensors for speed recording a neces-sity in motor control. The installation of a bearing with integral sensor wasconsidered to be the best solution.

SKF Sensor-Bearing Units contrib-ute to the outstanding performance

of the three-phase drive. The SKFSensor-Bearing Unit, which does notrequire any extra space, is located in a protected position in the motor andyields a uniform and reliable signal.Thanks to the unit concept, only onefitting operation is required to get thebearing and the sensor functionsinstalled. As quality and function arealready checked in bearing manufac-ture, minimum effort is required forsystem integration.

The SKF Sensor-Bearing Unit occupies no extra space, is wellprotected inside the motor and provides a reliable and steadysignal

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Selection of bearingsizeSKF Sensor-Bearing Units carry ratherhigh radial loads as well as axial loadsin both directions. They are suitablefor high speeds and robust in opera-tion and maintenance. The sensor unitintegral with the bearing enablesrecording of operating data.

The selection of the correct size ofSKF Sensor-Bearing Unit depends onthe same factors as that of a normaldeep groove ball bearing, as far asbearing function is concerned. Bearinglife is determined on the basis of theload carrying capacity of the bearingand the loads and operating conditionsof the application, using the normalmethods. The bearing data can beseen from the product table.

Unit arrangementTwo bearings are normally required tosupport a shaft – a locating and a non-locating bearing. Since the SKFSensor-Bearing Unit is mainly to beused as a locating bearing, the oppositeshaft end must be supported by a non-locating bearing. If high axial loads acton the SKF Sensor-Bearing Unit in bothdirections, it should be mounted in sucha way that the higher axial loads act onthe bearing outer ring face opposite tothe sensor unit.

Radial locationSKF Sensor-Bearing Units are designedfor the following application conditions:

� rotating inner ring with rotating load� stationary outer ring with stationary

load

In accordance with the general recom-mendations in these cases, the innerring has a tight fit on the shaft and theouter ring a loose fit in the housingbore.

The sensor unit connection cableemerges from the bearing position inthe radial direction and determines theposition of the outer ring relative to thehousing. A sufficiently dimensionedcable duct must be provided in thehousing or housing cover.

It is recommended that the cableprotruding from the sensor body, isprotected against excessive rotationby a radial notch in the housing. Thatnotch should be of a circumferentialwidth of 9 to 15 mm. The notch depthshould reach at least the side face ofthe bearing outer ring (➔ fig ). Toavoid stress on the sensor body, it isrequired that the cable outlet do nottouch the notch during assembly,therefore it is recommended that theSensor-Bearing Unit is positionedangularly during the whole assemblyprocess.

However, in the case of loose hous-ing fit – and when the stationary loadis including additionally dynamic forces– vibration can cause slight rotation ofthe outer ring (creeping). In order toget the best signal generation and pro-cessing the position of the cable mustbe fixed. To prevent creeping, we re-commend the insertion of a nitrile rub-ber O-ring into the circumferentialgroove in the outer ring outside diam-eter (➔ fig ).1

1

Application of units

Axial location of the outer ring of smallbearings using a snap ring in the housing bore

1Fig

2Fig

Notch in the housing and location ofouter ring in circumferential directionby an O-ring inserted in the snap ringgroove

1 Product information 2 Recommendations 3 Product dataPage ............ 3 Unit arrangement Page ............ 16

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1 Product information 2 Recommendations 3 Product dataPage ............ 3 Axial location Page ............16

2

Axial locationThe inner ring with tight fit is normallylocated in the axial direction on bothsides, e.g. by a shaft shoulder, a dis-tance sleeve or a snap ring. The axiallocation of the outer ring depends onthe bearing size.

� With bearings up to and including a bore diameter of 25 mm the outerring is located axially on the sideopposite to the sensor unit by ashoulder in the housing bore. If thebearing is only subjected to lightloads or not loaded at all in theopposite direction, a snap ringengaging a groove in the housingbore is sufficient for axial location onthe sensor side. Between snap ringand sensor body an annular steelsheet washer must be fitted, abut-ting the sensor body over its entirewidth (➔ fig ). A sufficiently dimen-sioned recess must be provided inthe housing for taking up the sensorunit connecting cable.

2

In the event of higher axial loads occurring we recommend location ofthe bearing with an end cover boltedto the housing via a snap ring in thegroove of the outer ring. In this casea recess must be provided as cableduct in the cover (➔ fig ). The abut-ment dimensions can be found in theproduct table.

� With bearings having a bore diam-eter of 30 mm and more the outerring is fitted in such a way that theside face opposite to the sensor unitabuts a housing shoulder. There aretwo ways of axially locating thebearing on the sensor side:

A thin-walled distance sleeve slotted in the axial direction is insert-ed into the housing bore so that itabuts the bearing and location isprovided by a snap ring. The sleeveinside diameter must match the out-side diameter of the sensor unit, andits outside diameter must correspondto the housing bore diameter. Thewidth of the sleeve slot must bedetermined in accordance with thedimensions of the connecting cable

3

where it emerges from the sensorunit. The distance sleeve covers thedistance between the outer ring sideface and the snap ring and must beso wide that the snap ring, wheninserted into the annular groove,abuts the distance sleeve, but notthe sensor ring (➔ fig ).

With these bearing sizes the ring side face not covered by the sensorbody in most cases, however, is suf-ficiently wide to allow reliable loca-tion using an end cover bolted to thehousing. The cover abuts the outerring side face and must be providedwith a recess for the cable (➔ fig ).The abutment dimensions can befound in the product table.

If the SKF Sensor-Bearing Unit is usedas a non-locating bearing, which shouldonly be considered in exceptionalcases, the outer ring must be free tomove axially in both directions. Caremust be taken that this axial displace-ment is not impeded by the connectingcable, while outer ring rotation shouldbe prevented.

5

4

Axial location of the outer ring of smallbearings using a snap ring in the outerring and an end cover

Axial location of the outer ring of largerbearings using a distance sleeve and a snap ring in the housing bore

Axial location of the outer ring of largerbearings using an end cover

3Fig 4Fig 5Fig

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1 Product information 2 Recommendations 3 Product dataPage ............ 3 Electrical interface data, mounting Page ............16

Electrical interface dataActive sensor operation requires a regulated supply voltage of 5 to 24 V.Signal output is effected via an opencollector (➔ fig ). Resistors insertedbetween the conductor connected tothe voltage supply and the conductorsfor the output signals limit the outputcurrent to 20 mA (➔ table ). For signal output features ➔ table .2

1

6

II

III

I

IV

R

R < 20 mA

< 20 mA

+ V

0 V

Signal B

Signal A

Sen

sor

+ V

0

Signal A

Voltage Recommended resistors R P

V Ω W

5 270 0,259 470 0,2512 680 0,2524 1 500 0,5

Electrical parameters

Signal output features

Technical data

Signal type Digital square

Number of signals 2

Phase shift 90 degrees

Duty cycle 50 % of a period

6Fig

Circuit diagram

MountingOn mounting, SKF Sensor-BearingUnits must be handled with great carein order to avoid damage to the sen-sor unit and the connecting cable.

First the bearing ring having a tightfit, which is the inner ring in this case,is pressed onto its seating surface.The pressing-in force must be appliedonly onto a mounting sleeve abuttingthe inner ring side face, either by handor using a press (➔ fig ). The press-ing-in force must under no circum-stances be applied to the sensor unit.

Bearing mounting is simplified whenthe bearings are heated. However,only a temperature-controlled electrichot plate must be used and the tem-perature of 80 °C must not be exceed-ed. The bearing must not be placeddirectly on the hot plate, but a mandrelmust be inserted in the bearing bore.This mandrel transfers the heat fromthe hot plate to the bearing inner ringand ensures an adequate distancefrom the bearing to the hot plate (➔ fig ).

In order to insert the bearing withloose outer ring fit into the housing, itmust be centred relative to the hous-ing bore and must not be tilted ormisaligned during insertion (➔ fig ).

Above all, care must be taken thatthe cable outlet does not touch otherparts, and that the connecting cablepasses through the cable hole andcannot be bent or squeezed on mount-ing.

For special requirements, SKF pro-vides on request customised assist-ance in optimising the process ofmounting and connection.

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8

7

Warning

When heating the bearing the con-necting cable must not come intocontact with the hot plate (➔ fig ).An induction heater must not beused for heating SKF Sensor-BearingUnits as this would cause fatal dam-age to the electronic components.

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2Table

1Table

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1 Product information 2 Recommendations 3 Product dataPage ............ 3 Mounting and maintenance Page ............ 16

2

Pressing of innerring onto the shaftseat using amounting sleeve

Heating of bearingbefore mountingonto the shaft

Vertical assemblyof end-frame andSensor-BearingUnit

Lubrication and maintenanceThe SKF Sensor-Bearing Units fromthe standard range are supplied assealed bearing units ready for mount-ing. They are filled with a polyureagrease suitable for the temperaturerange of the sensor unit (between –40and +120 °C), ensuring reliable lubri-cation for the entire bearing life. Thegrease fill is adapted to the bearingsizes. Thus SKF Sensor-Bearing Unitsare maintenance-free.

7Fig

8Fig

9Fig

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1 Product information 2 Recommendations 3 Product dataPage ............ 3 Page …………12 General data

DesignAn SKF Sensor-Bearing Unit (➔ fig )consists of

� a standard deep groove ball bearingwith one seal and one snap ringgroove in the outside surface of theouter ring (a)

� the magnetised impulse ring (b)l the sensor body (c)l the connecting cable (d).

1The sensor body protecting two

embedded Hall cells is attached to theouter ring – a patented SKF solution.

The multiwire connecting cableextending in radial direction, whichconnects the SKF Sensor-Bearing Unitand the signal processing electronics,has a standard length of approximately500 mm. In order to take into accountthe different requirements to the inter-face between the SKF Sensor-Bearing

General unit data

d

c

b

a

II IIII I VII IIII IV

II IIII IV

1 2 3

On the one side the bearing is fittedwith a standard seal sealing againstthe inner ring shoulder. On the oppo-site side the impulse and sensor bodyform an effective labyrinth seal.

The impulse ring is a compositemagnetised ring. The number of northand south poles (between 32 and 80)depends on the size of the bearing.The impulse ring is attached to thebearing inner ring.

Different versions of connecting cableends

Components of SKF Sensor-Bearing Unit

2Fig1Fig

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1 Product information 2 Recommendations 3 Product dataPage ............ 3 Page …………12 General data

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Unit and the electronic unit normallydeveloped by the customer, the differ-ent unit sizes are available with freecable end, and can be delivered onrequest with two different standardconnectors (➔ fig ).

Version 1 Free cable endVersion 2 Plug connection AMP

Superseal, AMP Nos.282106-1 and 282404-1

Version 3 Plug connection AMPMate-N-Lock, AMP Nos.350779-1, 350811-1 and350924-1

2

DimensionsSKF Sensor-Bearing Units are basedon deep groove ball bearings of series62. Their boundary dimensions areidentical with those of dimensionseries 02 in accordance with ISO 15:1998. However, more space must beprovided in the axial direction, as theunit is wider due to the integral sensor.

TolerancesThe bearings of the SKF Sensor-Bearing Units are manufactured to normal tolerances as standard. Thevalues of these tolerances conform toISO 492:1994.

Radial internal clearanceIn accordance with the requirements ofthe major applications, especially ofelectric machine constructions, SKFSensor-Bearing Units have radial inter-nal clearance C3 as specified for deepgroove ball bearings in ISO 5753:1991. The values given in tableapply to bearings in unmounted con-dition under zero measuring load.

Permissible speedsThe SKF Sensor-Bearing Unit is suit-able for the limiting speed valid for thecorresponding deep groove ball bear-ing with seals. If the bearings are to beoperated at higher speeds than indi-cated in the product table, SKF shouldfirst be contacted.

Operating temperature rangeExtensive long-term testing in the la-boratory showed that our SKF Sensor-Bearing Units can be used in a tempera-ture range between –40 and +120 °C.For constant temperatures exceeding+120 to +150 °C special versions areavailable, subject to in-depth checkingof the application in question.

1

Bore Radial internal clearance C3

d min max

mm µm

15 11 2520 13 2825 13 28

30 13 2840 15 3345 18 36

Radial internal clearance of SKF Sensor-Bearing Units

1Table

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1 Product information 2 Recommendations 3 Product dataPage ............3 Page …………12 Sensor-Bearing Units

d 15 – 45 mm

Bearing Sensor unit Mass DesignationPrincipal Basic load ratings Fatigue Limiting Number Period Phase Unit with 500 mm long cabledimensions dynamic static load speed of accuracy shift but without connectord D B C C0 limit pulses

Pu

mm kN kN r/min – % degrees kg –

15 35 11 8,06 3,75 0,16 13 000 32 ± 3 90 ± 30 0,06 BMB-6202/032S2/EA002A

20 47 14 13,5 6,55 0,28 10 000 48 ± 3 90 ± 30 0,15 BMB-6204/048S2/EA002A

25 52 15 14,8 7,8 0,34 8 500 48 ± 3 90 ± 30 0,18 BMB-6205/048S2/EA002A

30 62 16 20,3 11,2 0,48 7 500 64 ± 4 90 ± 45 0,22 BMB-6206/064S2/EA002A

40 80 18 32,5 19 0,8 5 600 80 ± 5 90 ± 45 0,40 BMB-6208/080S2/EB002A

45 85 19 35,1 21,6 0,92 5 000 80 ± 5 90 ± 45 0,44 BMB-6209/080S2/EB002A

d d1 D D1D2

r 2

r 2

r1

r1

B

b

C 5,5

min 0,5

d2

6,5

7

6,2

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1 Product information 2 Recommendations 3 Product dataPage ............3 Page …………12

3

Dimensions Abutment and fillet dimensions

d d1 d2 D1 D2 b C r1,2 da db db Da ra≈ ≈ min min min max max max

mm mm

15 21,5 19,5 30,4 34,4 1,35 2,06 0,6 19 19 19,4 31 0,6

20 28,5 26,4 40,6 46,4 1,35 2,06 1 25 25 26,3 42 1

25 34 31,8 46,3 51,4 1,35 2,46 1 30 30 31,5 47 1

30 40,3 37,8 54,1 58 1,9 3,28 1 35 35 37,5 57 1

40 52,6 48 69,8 75 1,9 3,28 1,1 46,5 46,5 47,5 73,5 1

45 57,6 53 75,2 78,8 1,9 3,28 1,1 51,5 51,5 52,5 78,5 1

Da db da D2

r a

r a

+1

r a

Bore diameter of end cover ≥ D2 + 1 (mm)

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The SKF range of sensorised bearingsis not limited to deep groove ball bear-ings. In the course of the develop-ment, the sensor concept was imple-mented with other bearing types aswell.

Sensorised bearingunits for road vehiclesToday pioneering developments inengineering often start in vehicle con-struction. The demand for constantlydecreasing fuel consumption results inthe components becoming more andmore compact and more and morefunctions being integrated. Withrequirements of passive and activesafety increasing this might present a contradiction in terms.

The anti-lock braking system forexample significantly increased theactive safety of a car, and the inte-gration of the sensors into the bearing,which was achieved by SKF, made it a top product. Less components, morecompact construction and simplifiedmounting are the OEM benefits. Theuser benefits are uniform and high signal accuracy, minimum liability tointerference and long service life.

Today millions of SKF wheel bearingunits with integral sensors are in use,in cars as well as in trucks.

Further SKF sensorised bearingunits

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Sensorised bearingunits for rail vehiclesOperating conditions in rail vehicles are especially arduous. The bearingsmust not only tolerate vibration, impactloads, high loads and extreme tempera-tures, but must ensure high distancesdriven with high operational reliabilityover great distances and with longmaintenance intervals. The same is trueof the integral sensors which controlthe braking system, ensure optimumfrictional engagement of the drivingwheels on starting-up and detect thedirection of rotation.

The SKF sensorised bearings for railvehicles meet these requirements.They are compact, ready-to-mount andeasy-to-install systemised solutions,having a cylindrical roller bearing (CRU)or taper roller bearing (TBU) as basicbearing.

Apart from these bearing units withspeed sensors, bearing units with tem-perature sensors are also availablefrom SKF. They allow immediate andpermanent monitoring of bearing tem-perature, preventing hot-running axle-boxes and bearing damage in opera-tion.

Sensorised bearingunits for tractionmotorsBased on its many years of experi-ence with sealed and greased for lifebearing units as well as integral speedand temperature sensors SKF develop-ed Traction Motor Bearing Units(TMBU).

The version for the non-driven sideis a deep groove ball bearing withflanged outer ring for attachment tothe motor case and, if required, withan inner ring flange for attachment tothe rotor shaft. These units can besupplied with or without integral speedand temperature sensors. Sealing ofthe bearing unit and position and attachment of the sensor are identicalwith the axlebox bearings.

The version for the drive side has a single row cylindrical roller bearingcombined with a four point contact ballbearing as basic bearings.

The SKF Traction Motor BearingConcept combines in one unit all func-tions important for the bearing arrange-ment, also including the insulation, ifrequired.

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development has also played a vitalrole, resulting in many examples ofepoch-making innovations.

The business of the Group consistsof bearings, seals, special steel and a comprehensive range of other high-tech industrial components. The experi-ence gained in these various fields provides SKF with the essential know-ledge and expertise required in order to provide the customers with the mostadvanced engineering products andefficient service.

SKF is an international industrial Groupoperating in some 130 countries and isworld leader in bearings.

The company was founded in 1907following the invention of the self-align-ing ball bearing by Sven Wingquist and,after only a few years, SKF began toexpand all over the world.

Today, SKF has some 40 000 em-ployees and around 80 manufacturingfacilities spread throughout the world.An international sales network includesa large number of sales companies andsome 7 000 distributors and retailers.Worldwide availability of SKF productsis supported by a comprehensive technical advisory service.

The key to success has been a con-sistent emphasis on maintaining thehighest quality of its products and services. Continuous invest-ment in research and

The SKF Group– a worldwide corporation

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SKF has developed the Channel concept infactories all over the world. This drasticallyreduces the lead time from raw material toend product as well as work in progress and finished goods in stock. The conceptenables faster and smoother informationflow, eliminates bottlenecks and bypassesunnecessary steps in production. TheChannel team members have the know-ledge and commitment needed to share theresponsibility for fulfilling objectives in areassuch as quality, delivery time, productionflow etc.

The SKF Group is the first major bearingmanufacturer to have been granted approvalaccording to ISO 14001, the internationalstandard for environmental managementsystems. The certificate is the most com-prehensive of its kind and covers more than60 SKF production units in 17 countries. The SKF Engineering & Research Centre

is situated just outside Utrecht in TheNetherlands. In an area of 17 000 squaremetres (185 000 sq.ft) some 150 scientists,engineers and support staff are engaged inthe further improvement of bearing perform-ance. They are developing technologiesaimed at achieving better materials, betterdesigns, better lubricants and better seals – together leading to an even better under-standing of the operation of a bearing in itsapplication. This is also where the SKF LifeTheory was evolved, enabling the design of bearings which are even more compact and offer even longer operational life.

SKF manufactures ball bearings, roller bearings and plain bearings. The smallest are just a few millimetres (a fraction of aninch) in diameter, the largest several metres.SKF also manufactures bearing and oil seals which prevent dirt from entering and lubricant from leaking out. SKF’s subsidiaries CR and RFT S.p.A. are amongthe world's largest producers of seals.

® SKF is a registered trademark of the SKF Group.

© Copyright SKF 2003The contents of this publication are thecopyright of the publisher and may notbe reproduced (even extracts) unlesspermission is granted. Every care hasbeen taken to ensure the accuracy ofthe information contained in this pub-lication but no liability can be acceptedfor any loss or damage whether direct,indirect or consequential arising out ofthe use of the information containedherein.

Publication 5106/II E · December 2003

Printed in Sweden on environmentally friendly, chlorine-free paper (Multiart Silk) by SG Tryck AB.

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